X-Ray Emissions from Three-Dimensional Magnetohydrodynamic Coronal Accretion Flows
X-Ray Emissions from Three-Dimensional Magnetohydrodynamic Coronal Accretion Flows
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DOI：
10.1093/pasj/60.2.399
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发表时间：
2008-01
影响因子：
2.3
通讯作者：
N. Kawanaka;Y. Kato;S. Mineshige
中科院分区：
文献类型：
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作者：
N. Kawanaka;Y. Kato;S. Mineshige
基于三维磁流体动力学（MHD）模拟计算了黑洞吸积盘-日冕系统的辐射谱及其时变特性。在解释活动星系核的光谱特性时，经常假设它们由一个几何上薄的光学厚盘和围绕薄盘的热的光学薄日冕组成。对于日冕模型，我们采用了Y. Kato和同事，而对于薄磁盘，我们假设标准类型的磁盘。我们进行了蒙特-卡罗辐射传输模拟的日冕，同时考虑到康普顿散射的软光子从薄盘热电子和日冕辐射加热的薄盘，发射黑体辐射。通过调整MHD冕流的密度参数，我们可以得到与典型Seyfert星系一致的出射光谱。此外，我们发现快速的时间变化的X射线发射光谱，起源于由磁流体日冕中的磁旋转不稳定性产生的密度波动。并简要讨论了包括铁荧光线发射在内的反射分量的特征。
We calculated the radiation spectrum and its time variability of a black-hole accretion disk–corona system based on a three-dimensional magnetohydrodynamic (MHD) simulation. In explaining the spectral properties of active galactic nuclei, it is often assumed that they consist of a geometrically thin, optically thick disk and hot, optically thin corona surrounding the thin disk. As for a model of the corona, we adopted the simulation data of threedimensional, non-radiative MHD accretion flows calculated by Y. Kato and coworkers, while for a thin disk we assumed a standard-type disk. We performed Monte-Carlo radiative transfer simulations of the corona, while taking into account the Compton scattering of soft photons from the thin disk by hot thermal electrons and coronal irradiation heating of the thin disk, which emits blackbody radiation. By adjusting the density parameter of the MHD coronal flow, we could produce emergent spectra that are consistent with those of typical Seyfert galaxies. Moreover, we found rapid time variability in the X-ray emission spectra, originating from a density fluctuation produced by am agnetorotational instability in the MHD corona. The features of reflection component including iron fluorescent line emission are also briefly discussed.